The present invention relates to a method and apparatus for dyeing a plastic lens with a sublimation dye.
With various kinds of dyeing methods (vapor phase methods) having conventionally been proposed, a plastic lens and, especially, plastic lenses for spectacle lenses are dyed with a sublimation dye by heating and sublimating the sublimation dye. Details of these various kinds of dyeing methods are disclosed in, for example, references 1 to 4.
In the method of dyeing a plastic lens described in reference 1, a dyeing material is applied to a print medium, and the print medium is heated in a vacuum while being opposed to the plastic lens. The dyeing material is obtained by dissolving a sublimation colorant or dispersing it as fine particles, and is applied to a print substrate by a printer based on color data managed by an electronic calculator. The print substrate is heated by a heating means while its coated surface is opposed to the plastic lens in a noncontact state. The sublimation colorant sublimates upon heating the print substrate in a vacuum.
In the method of dyeing a plastic lens described in reference 2, the plastic lens and dyeing substrates are held in an apparatus by a holding means, and the two surfaces of the plastic lens are dyed at once. The dyeing substrates are coated with a dyeing material obtained by dissolving a sublimation colorant or dispersing it as fine particles. These substrates are opposed to the convex and concave surfaces of the plastic lens by first and second opposing means, respectively. The first opposing means opposes the coated surface of one substrate to the convex surface of the plastic lens in a noncontact state. The second opposing means opposes the coated surface of the other substrate to the concave surface of the plastic lens in a noncontact state. The substrates opposed to the plastic lens by these first and second opposing means are heated by a heating means. This heating takes place after the apparatus is evacuated into an almost vacuum atmosphere by an exhaust device.
In the method of dyeing a plastic lens described in reference 3, an apparatus is cooled so that the color reproducibility stabilizes. A dyeing apparatus which performs this method includes a dyeing substrate, vacuum atmosphere forming means, heating means, and cooling means. The substrate is coated with a sublimation dye, and placed in the dyeing apparatus. The vacuum atmosphere forming means evacuates the dyeing apparatus into an almost vacuum atmosphere. The heating means is placed in the dyeing apparatus, and heats the substrate. The cooling means is in contact with the outer wall of the dyeing apparatus, and cools the dyeing apparatus by heat exchange in the contact portion between the cooling means and that outer wall.
In the method of dyeing a plastic lens described in reference 4, at least one of the plastic lens and a holding member which holds a sublimation dye is rotated or vibrated during heating. The adoption of this method allows the plastic lens to be evenly dyed free from any variation. The holding member is heated by a heating member, and the plastic lens is heated by a lens temperature controller.    [Reference 1] Japanese Patent Laid-Open No. 2001-59950    [Reference 2] Japanese Patent Laid-Open No. 2001-215306    [Reference 3] Japanese Patent Laid-Open No. 2004-69905    [Reference 4] Japanese Patent Laid-Open No. 2005-25130
In the dyeing apparatuses described in references 1, 3, and 4 each, because the lens and the dyeing substrate are separately arranged in the vacuum device, their loading/unloading is so cumbersome as to require a considerable time. Also, the dyeing apparatuses described in these references each require a mechanism or means for adjusting the interval between the lens and the dyeing substrate.
In the dyeing apparatus described in reference 2, because the intervals between the print substrates and the lens are fixed, an appropriate adjusting means is necessary to change these intervals.